I started work a few weeks ago on an n64p, and i'm posting here to share a few ideas and hopefully keep me motivated.
Ok, so i've got everything running from a battery, etc. and am at the point now where i need to get it into a case

Here's what i've done so far
I decided i wanted RGB on my portable so that meant modifying a US n64 to output RGB and play my PAL games.
To do this i simply removed the PIF chip from a PAL n64 and put it into a US n64

This chip is what interfaces with the controllers and the CIC lockout chip in the cartridge, by using a PAL chip (PIF(P)-NUS) it essentially becomes a PAL machine.
I also wanted RGB, i got this by tapping into "U4" the VDC-NUS pins and running them to an amplifier circuit i found here

This boosts the signal to an acceptable output level to drive a tv/screen

I also wanted an expansion pak in my portable, i did a few tests for overall power draw at 7.4V.

It seems the extra ram in the expansion pak increases draw by about 200mA in normal games and about 300mA in those that used it!, since i intend to use quite a small battery, 200mA is fairly significant to battery life and also heat production.
An expansion pak also takes up room and is awkward to heatsink, so i replaced the 18Mbit ram chips on the n64 mobo with 36Mbit ram from a couple of expansion paks

The soldering is a little untidy because i used an iron and braid whereas hot-air would have been a bit neater.
But it works fine and games detect the expansion pak as normal, i did some stress tests with Perfect Dark multiplayer with 8 bots and there were no crashes for over 4 hours, this is longer than i would ever play the portable and i don't forsee it crashing after that time.

It still requires the jumper pak inserted, but it should be easy enough to hand-wire the resistors etc to the mobo without increasing the boards height.
This meant that current draw was reduced to about 700mA when playing majora's mask and 600mA on non-expansion pak games.

thanks, the pins are a little too small for hand-soldering so you do have to be careful, i usually try to warm up all the pins, then wipe solder over all of them at once, and use desoldering braid to clean them up. Ideally you would use hot-air.

The good news is - I've removed the two original 18Mbit Rambus chips from my N64 and soldered on two 36Mbit chips from two expansion packs. This has been tested with Turok 2 for the past hour - it detected the extra memory and has been working fine so far!

The bad news is - this unfortunately still requires the use of the jumper pack as I couldn't find a simple way of soldering the termination resistors directly onto the N64 motherboard (believe me, I tried).

At one point, I did try soldering some separate resistors to the relevant pins (where the expansion pack connector used to be), but the N64 wouldn't boot. This is more than likely because I didn't have any 51ohm resistors at the time, only 62 ohms.

So, for the moment, I have the jumper pack soldered directly to the N64 and it only boots if you solder the extra couple of ground pins. I'm sure that using separate resistors would work fine, so I'll get and order some soon.

I've also been checking out some photos of the SGI / Ultra 64 development board... Interestingly, it uses 12 separate termination resistors next to the Rambus chips. These resistors appear to all be 40.2ohms (due to the shorter track lengths and different track design.)

It shouldn't be too difficult to find the correct resistor values for the N64 and it might even work fine with 51 ohms anyway (I'll try it soon).

OzOnE.

The rest of that thread, before and after, is a good read. Amazed he did not make his own topic. No proof, so he could by lying, but he seems to know what he is doing well enough that doing as he said he did seems to be a trivial task for someone on his skill plane.

I thought a little more about the case today, i'm going with a minimalist approach, i'm thinking clean lines simple design etc.
This led me to think about the power switch, it needs to switch about an amp, which means it'll have to be fairly large and unsightly, not what i want.

So i thought about using a momentary switch to turn the portable on and off, like the slimline ps2.
To do this i made a little circuit as a quick prototype to what i might use in my portable.

I made it from parts i had laying around so i still need to tweak the circuit a little before it's ideal, the big power MOSFET is overkill (it can switch 30A!) but it works well, one push of the button turns the power on, another turns it off. And it only drops about a tenth of a volt so it's more than suitable.

I'll probably work on it a bit more, add a delay to the switch or something so it works like, [press--hold for 1 sec--turn on] etc. and may integrate with a couple of other ideas i've got.

When it's done i'll draw up a diagram if anyone wants it so they can check it out themselves.